rc: refactor loop avoidance again, fix typo from historic commit

https://github.com/pfsense/pfsense/commit/46a7c9aae#diff-9f6cbcc34208589ed90d936a29cbe8c9R120

src/etc/rc.newwanipv6

@@ -112,13 +112,6 @@ link_interface_to_track6($interface, "update");
 system_resolvconf_generate();
 system_hosts_generate();
 
-if (is_ipaddrv6($curwanipv6) && $curwanipv6 == $oldipv6) {
-    if (in_array($config['interfaces'][$interface]['ipaddrv6'], array('pppoe', 'pptp', 'ppp'))) {
-        /* PPP reconnect loop avoidance */
-        return;
-    }
-}
-
 /*
  * We need to force sync VPNs on such even when the IP is the same for dynamic interfaces.
  * Even with the same IP the VPN software is unhappy with the IP disappearing, and we
@@ -127,13 +120,18 @@ if (is_ipaddrv6($curwanipv6) && $curwanipv6 == $oldipv6) {
 if (!is_ipaddrv6($oldipv6) || $curwanipv6 != $oldipv6 || !is_ipaddrv6($config['interfaces'][$interface]['ipaddrv6'])) {
     if (is_ipaddrv6($curwanipv6)) {
         @file_put_contents("/var/db/{$interface}_cacheipv6", $curwanipv6);
-    }
 
-    if ($curwanipv6 != $oldipv6 && is_ipaddrv6($oldipv6)) {
+        if ($curwanipv6 == $oldipv6) {
+            if (in_array($config['interfaces'][$interface]['ipaddr'], array('l2tp', 'ppp', 'pppoe', 'pptp'))) {
+                /* PPP reconnect loop avoidance */
+                return;
+            }
+        } else {
             if (does_interface_exist($interface_real)) {
                 mwexec("/sbin/ifconfig {$interface_real} inet6 {$oldipv6} delete");
             }
         }
+    }
 
     system_routing_configure($interface);
     setup_gateways_monitor();